One typical rocking chair of the prior art includes a pair of rocking cams mounted in side-by-side relationship on opposite sides of the chair respectively. The cams are rigidly fixed to the seat frame and have arcuate surfaces engaged against a fixed base with tension springs located between the cams and the base to impose a constant bias on the cams. The cams are rockable along an arcuate path determined by the shape of the cam surface which engages the base. Such a rocker is shown by way of example in U.S. Pat. No. 3,730,585. While the cam construction of these types of rockers have the advantage of simplicity, the rocking motion of the seat including the path of movement of the seat is governed by the shape of the cams which, at times, can produce undesirable forward or rearward lurching movement at the extremes of travel.
Another type of rocking chair utilizes linkage mechanisms to provide rocking as well as translatory movement of the seat relative to the base to achieve a different type motion similar to a glider chair. Such a chair is shown, for example, in U.S. Pat. Nos. 4,536,029 and 4,544,201. While the use of linkages enable a predetermined rocking and gliding motion to be achieved, they are more complicated when compared to the conventional cam assemblies described above. They also suffer from instability in the side-to-side direction of the chair thus requiring torque tubes to overcome this drawback.